Coquillettidia (Culicidae, Diptera) mosquitoes are natural vectors of avian malaria in Africa

<p>Abstract</p> <p>Background</p> <p>The mosquito vectors of <it>Plasmodium </it>spp. have largely been overlooked in studies of ecology and evolution of avian malaria and other vertebrates in wildlife.</p> <p>Methods</p> <p><it>Plasmodium </it>DNA from wild-caught <it>Coquillettidia </it>spp. collected from lowland forests in Cameroon was isolated and sequenced using nested PCR. Female <it>Coquillettidia aurites </it>were also dissected and salivary glands were isolated and microscopically examined for the presence of sporozoites.</p> <p>Results</p> <p>In total, 33% (85/256) of mosquito pools tested positive for avian <it>Plasmodium </it>spp., harbouring at least eight distinct parasite lineages. Sporozoites of <it>Plasmodium </it>spp. were recorded in salivary glands of <it>C. aurites </it>supporting the PCR data that the parasites complete development in these mosquitoes. Results suggest <it>C. aurites</it>, <it>Coquillettidia pseudoconopas </it>and <it>Coquillettidia metallica </it>as new and important vectors of avian malaria in Africa. All parasite lineages recovered clustered with parasites formerly identified from several bird species and suggest the vectors capability of infecting birds from different families.</p> <p>Conclusion</p> <p>Identifying the major vectors of avian <it>Plasmodium </it>spp. will assist in understanding the epizootiology of avian malaria, including differences in this disease distribution between pristine and disturbed landscapes.</p

Diversity, Loss, and Gain of Malaria Parasites in a Globally Invasive Bird

Invasive species can displace natives, and thus identifying the traits that make aliens successful is crucial for predicting and preventing biodiversity loss. Pathogens may play an important role in the invasive process, facilitating colonization of their hosts in new continents and islands. According to the Novel Weapon Hypothesis, colonizers may out-compete local native species by bringing with them novel pathogens to which native species are not adapted. In contrast, the Enemy Release Hypothesis suggests that flourishing colonizers are successful because they have left their pathogens behind. To assess the role of avian malaria and related haemosporidian parasites in the global spread of a common invasive bird, we examined the prevalence and genetic diversity of haemosporidian parasites (order Haemosporida, genera Plasmodium and Haemoproteus) infecting house sparrows (Passer domesticus). We sampled house sparrows (N = 1820) from 58 locations on 6 continents. All the samples were tested using PCR-based methods; blood films from the PCR-positive birds were examined microscopically to identify parasite species. The results show that haemosporidian parasites in the house sparrows' native range are replaced by species from local host-generalist parasite fauna in the alien environments of North and South America. Furthermore, sparrows in colonized regions displayed a lower diversity and prevalence of parasite infections. Because the house sparrow lost its native parasites when colonizing the American continents, the release from these natural enemies may have facilitated its invasion in the last two centuries. Our findings therefore reject the Novel Weapon Hypothesis and are concordant with the Enemy Release Hypothesis

Nested cytochrome B polymerase chain reaction diagnostics underestimate mixed infections of avian blood haemosporidian parasites: Microscopy is still essential

Numerous polymerase chain reaction (PCR)-based methods have been developed and used increasingly to screen vertebrate blood samples for the diagnosis of haemosporidian blood parasites (Sporozoa, Haemosporida), but a rigorous evaluation of the sensitivity of these methods for detecting mixed infections of different haemosporidian species belonging to the same and different genera and subgenera is lacking. This study links the information obtained by nested cytochrome b PCR and traditional microscopy in determining mixed haemosporidian infections in naturally infected birds. Samples from 83 individual passerine birds with single infections of Haemoproteus or Plasmodium spp., as determined by mitochondrial DNA amplification, also were investigated by microscopic examination of stained blood films. Thirty-six samples (43%) were found to harbor mixed Haemoproteus, or Plasmodium spp. infections, or both. Thus, the PCR assays alone underestimate the Occurrence of mixed infections of haemosporidian parasites in naturally infected birds. To determine the true species composition of the haemosporidians in each individual host, PCR diagnostics need to be improved. Specific primers for Haemoproteus spp. and Plasmodium spp. should be developed. Ideally, a combination of the approaches of both microscopy and PCR-based methods is recommended for this purpose